In recent years, there has been realized a cooking apparatus which incorporates, as control means, a microprocessor comprising semiconductor large-scale integrated circuits, so that various cooking functions may be performed with simple circuit arrangements and simple operational procedures.
Such cooking functions typically includes a timer operation, a temperature operation, an output control operation, a delay time operation or combinations of such operations above-mentioned. Here, it is to be noted that the timer operation means that the cooking apparatus is operated for the desired period of time, the temperature operation means that the cooking apparatus is operated until food to be cooked is heated upto the desired temperature or that the cooking apparatus is operated for maintaining such desired temperature after such desired temperature has been reached, the output control operation means that the cooking apparatus is operated with the heating energy set to the desired value, and the display time operation means that, when the desired cooking completion time is being preset, the cooking apparatus is automatically started operating so that the cooking be finished at such desired completion time.
In controlling a combined operation of cooking functions above-mentioned, for example, when combining the timer operation with the delay time operation, the cooking apparatus can be set so as to start cooking at the time that the period of time preset for the timer operation is subtracted from the preset cooking completion time.
However, when intending to combine the temperature operation with the delay time operation, a period of time during which food to be cooked is heated to the preset temperature is not constant and varies with the contents of the food to be cooked. It is therefore not possible to calculate the period of time to be subtracted from the preset cooking completion time in order to find the cooking starting time. Such combination operation has therefore not been realized yet.
Furthermore, in such a cooking apparatus, there have been cases where the door of the cooking apparatus is opened during the supply of heating energy, for the purpose of making sure of the cooking condition, or accidentally. Therefore, there has advantageously been disposed a door open detection means for the safety purposes, whereby the operation of the cooking apparatus is stopped simultaneously with opening of the door. Thereafter, the door has been closed and a re-operation instruction has been give, so that heating energy has again been supplied.
However, such safety provision has produced an inconvenience in view of the automatic operation. Namely, in the case of the delay time operation, after various operational procesures have been applied to the cooking apparatus and before the cooking is not actually started, there have been cases where the door of the cooking apparatus is opened in order to make sure of how the food to be cooked is placed, or to apply additional treatments to the food to be cooked, or just accidentally. In such a case, according to the function of such safety provision the control of the cooking apparatus has not been reset to the normal status unless the re-operation instruction is given, even though the door has been closed. Thus, if application of such re-operation instruction has been failed, the cooking apparatus could not be started operating even though the predetermined time has come.
For the delay time operation, there have been cases where the operator is apart from the cooking apparatus before the cooking is actually started after various operational procedures have been applied to the cooking apparatus. In such a case, when the operator has forgotten the cooking start time and the cooking apparatus has therefore been started operating in the absence of the operator, not only necessary measures have not been taken, but also danger has been attended with if unexpected accidents such as burning of food to be cooked have taken place.
There have also been cases where, dependent on the kind of food to be cooked, it is desired to apply suitable treatments to the food to be cooked during the cooking, such as addition of seasonings. However, when the cooking has been started in the absence of the operator as above-mentioned or the operator, even though present near the cooking apparatus, has not become aware that the actual cooking start time had come and the cooking had been started, there has been a possibility of missing the opportunity for applying necessary treatment to the food during the cooking as above-mentioned. Particularly, when microwave energy is used as heating energy for the cooking, the cooking speed is very fast, so that it may well be that such opportunity for applying necessary treatment to the food during the cooking will easily be missed.